汉江中下游藻华暴发特征及生态流量阈值

Characteristics of algal bloom and its threshold of ecological flow in the middle and lower Hanjiang River

基于2015~2019年汉江中下游水文,水环境和水生态数据,采用主成分分析与冗余分析识别了河流藻华暴发防控的关键因子,拟合得到其调控阈值,然后,使用断面通量法和流速抑制法推求了抑制河流藻类水华暴发的生态流量.结果表明:汉江中下游藻类水华主要发生在枯水期,枯水期藻类优势种群为硅藻,小环藻为优势种,丰水期绿藻门和硅藻门是优势种群,小球藻为优势种.流速是影响汉江藻类生长的主控因子,当流速超过0.462m/s时,流速继续增大将抑制藻类生长.汉江中下游枯水期控制藻类水华的生态流量:沙洋断面流量为890m^(3)/s,潜江断面流量为918m^(3)/s,仙桃断面流量为953m^(3)/s,汉川断面流量为1075m^(3)/s.

Based on the hydrological,water environment,and water ecology data in the middle and lower Hanjiang River from 2015 to 2019,this paper uses principal component analysis and redundancy analysis to identify the key factors for the prevention and control of algal bloom outbreaks in the river,and obtained their regulatory thresholds by fitting.Then the ecological flow rate for inhibiting algal bloom outbreaks in the river was calculated by using the cross section flux method and the velocity inhibition method.The results showed that:Algal blooms in the middle and lower Hanjiang River mainly occurred in the dry season.In the dry season,the dominant algal populations were Bacillariophyta,chlorella were the dominant species.In the wet season,the dominant algal populations were Chlorophyta and Bacillariophyta,Chlorella sp.were the dominant species.Flow velocity is the dominant controlling factor affecting algae growth.We found the flow velocity exceeding 0.462m/s will inhibit algae growth.The ecological flow thresholds for controlling algal blooms in the middle and lower Hanjiang River during the dry season were 890m^(3)/s in the Shayang section,918m^(3)/s in the Qianjiang section,953m^(3)/s in the Xiantao section and 1075m^(3)/s in Hanchuan section.